a) \(\sqrt{x^2-10+25}\)=lx-5l=2

=>x=7 hoặc x=3

b) bình phường lên ta đc x^2-2x=25

từ đây bạn giải bình thường là đc chúc hk tốt

câu b bạn đã giải được chưa

tham khảo 

Australia is the smallest of the six continents and the only one having ‘one country’ in it. It remained cut off from the rest of the world after its geologic separation from Gondwanaland and its great distance from Europe, Americas and Asia. As a result very strange flora and fauna developed on this continent. It mostly consists of a flat, featureless land with no great rivers and no permanent snow covered mountains. The central lowlands are known for their underground water in their artesian basins. The Great Barrier Reef made up of coral rocks is a great tourist attraction.
Seasons in Australia are reverse of India because of the former’s location in Southern Hemisphere. It is mostly hot and dry as only 4% of the land is under cultivation. Wheat is grown extensively on the temperate grasslands in the Murray-Darling basin. Eucalyptus is the most common tree; nearly 700 varieties are found. The people have managed their limited land and water resources well.
Although the average density of the population is very low, most people live in the large cities and ports of the rainy eastern and south-eastern regions. Although the population is not much, Australia produces enough agricultural and industrial goods to meet its needs and still has plenty for export to other countries of the world.

TK: Australia is the smallest of the six continents and the only one having ‘one country’ in it. It remained cut off from the rest of the world after its geologic separation from Gondwanaland and its great distance from Europe, Americas and Asia. As a result very strange flora and fauna developed on this continent. It mostly consists of a flat, featureless land with no great rivers and no permanent snow covered mountains. The central lowlands are known for their underground water in their artesian basins. The Great Barrier Reef made up of coral rocks is a great tourist attraction.

Seasons in Australia are reverse of India because of the former’s location in Southern Hemisphere. It is mostly hot and dry as only 4% of the land is under cultivation. Wheat is grown extensively on the temperate grasslands in the Murray-Darling basin. Eucalyptus is the most common tree; nearly 700 varieties are found. The people have managed their limited land and water resources well.
Although the average density of the population is very low, most people live in the large cities and ports of the rainy eastern and south-eastern regions. Although the population is not much, Australia produces enough agricultural and industrial goods to meet its needs and still has plenty for export to other countries of the world.

Refer 

I love sudying English so I want to visit Australia - an English speaking country.

Australia is a country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands. It is the world's sixth-largest country by total area. Although Australia has no official language, English has always been entrenched as the national language.

a) đk: \(x\ge2\)

Ta có: \(\sqrt{x}+\sqrt{x-2}=2\sqrt{x-1}\) (đã sửa đề)

\(\Leftrightarrow x+2\sqrt{x\left(x-2\right)}=4\left(x-1\right)\)

\(\Leftrightarrow3x-4=2\sqrt{x^2-2x}\)

\(\Leftrightarrow9x^2-24x+16=4\left(x^2-2x\right)\)

\(\Leftrightarrow5x^2-16x+16=0\)

\(\Leftrightarrow5\left(x^2-\frac{16}{5}x+\frac{64}{25}\right)+\frac{16}{5}=0\)

\(\Leftrightarrow5\left(x-\frac{8}{5}\right)^2=-\frac{16}{5}\) vô lý

=> PT vô nghiệm

b) Đề chắc là: \(x^2+x+12=\sqrt{36}\)

\(\Leftrightarrow x^2+x+12-6=0\)

\(\Leftrightarrow\left(x^2+x+\frac{1}{4}\right)+\frac{23}{4}=0\)

\(\Leftrightarrow\left(x+\frac{1}{2}\right)^2=-\frac{23}{4}\) vô lý

=> PT vô nghiệm

đề đâu bạn

\(\Rightarrow x+3\ge4\\ \Rightarrow x\ge1\)

\(\left|x+3\right|\ge4\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3\ge4\\x+3\le4\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x\ge1\\x\le1\end{matrix}\right.\)

a)5-2x=3x+20

   5=3x+20+2x

   5=5x+20

=>5x+20=5

    5x=5-20

    5x=-15

   x=(-15):5

  x=-3

Bùi Ngọc Truongf Sơn làm nốt cho mình 2 bài còn lại đi

\(a,5-2x=3x+20\)

\(\Leftrightarrow-2x-3x=20-5\)

\(\Leftrightarrow-5x=15\)

\(\Leftrightarrow x=-3\)

\(b,5-\left(1-3x\right)=2x+4\)

\(\Leftrightarrow5-1+3x=2x+4\)

\(\Leftrightarrow5-1-4=2x-3x\)

\(\Leftrightarrow0=-x\)

\(\Leftrightarrow x=0\)

\(c,35-\left(5-2x\right)=7-\left(-3+3x\right)\)

\(\Leftrightarrow35-5+2x=7+3-3x\)

\(\Leftrightarrow35-5-7-3=-2x-2x\)

\(\Leftrightarrow20=-4x\)

\(\Leftrightarrow x=-5\)